1. Field of the Invention
The present invention relates to a remote key entry system of a motor vehicle, particularly to a remote key entry system providing an answerback sound in response to a radio key signal transmitted from a key unit.
2. Prior Art
Recently, most motor vehicles have a remote key entry system. Conventionally, such a system has a key unit and a vehicle side device receiving a radio key signal transmitted from the key unit for remote control of a vehicle. The remote key entry system provides an answerback signal to show completion of correct locking or unlocking of the vehicle. The answerback is, for example, flickering of a hazard lamp or producing of a buzzer sound.
However, a buzzer sound provided by the conventional remote key entry system has a fixed sound volume or tone to be audible in a noisy area. However, such buzzer sounds themselves may become noises. For example, the fixed buzzer sounds may be an annoyance to the neighbors particularly at midnight or in a place where a low noise is requested.